Comment 15 for bug 2015400

Verification done on jammy-proposed.

$ lxc launch ubuntu:jammy jammy-loop --vm
$ lxc shell jammy-loop

# apt update && apt install -y gcc
# gcc -o test-loop test-loop.c

# add-apt-repository -y -p proposed
# apt-cache madison linux-image-5.15.0-83-generic
linux-image-5.15.0-83-generic | 5.15.0-83.92 | http://archive.ubuntu.com/ubuntu jammy-proposed/main amd64 Packages
linux-image-5.15.0-83-generic | 5.15.0-83.92 | http://security.ubuntu.com/ubuntu jammy-proposed/main amd64 Packages

# apt install -y linux-image-5.15.0-83-generic

# echo "GRUB_DEFAULT='Advanced options for Ubuntu>Ubuntu, with Linux 5.15.0-83-generic'" >/etc/default/grub.d/99-default.cfg
# echo "GRUB_FORCE_PARTUUID=" >>/etc/default/grub.d/99-default.cfg
# update-grub && reboot

# uname -rv
5.15.0-83-generic #92-Ubuntu SMP Mon Aug 14 09:30:42 UTC 2023

...

default: works (fixed)

# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.15.0-83-generic root=UUID=16ad92d2-3cc7-4162-9ffe-b5c17b8acbe2 ro console=tty1 console=ttyS0

# ./test-loop
#

...

max_loop=0: works (expected)

# echo 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT max_loop=0"' >/etc/default/grub.d/99-maxloop.cfg
# update-grub && reboot

# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.15.0-83-generic root=UUID=16ad92d2-3cc7-4162-9ffe-b5c17b8acbe2 ro console=tty1 console=ttyS0 max_loop=0

# ./test-loop
#

...

max_loop=8: fails (expected)

# echo 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT max_loop=8"' >/etc/default/grub.d/99-maxloop.cfg
# update-grub && reboot

# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.15.0-83-generic root=UUID=16ad92d2-3cc7-4162-9ffe-b5c17b8acbe2 ro console=tty1 console=ttyS0 max_loop=8

# ./test-loop
open: /dev/loop8: No such device or address